The present invention relates to a casing structure surrounding blades that rotate within the casing, which structure, during blade rotation, will prevent any broken off blade parts from damaging the enclosing casing.
It is known from published patent application GB 2,288,639, EP 0 927 815 A2 and others, to provide containment structure that will prevent exit of a broken blade part from a fan to atmosphere via the cowl streamlined outer surface structure. However, in each case, the inner casing structure is penetrated and results in the need to replace it.